Measurement of Uranium and Plutonium in Solid Waste by Passive Photon or Neutron Counting and Isotopic Neutron Source Interrogation

摘要

A summary of the status and applicability of nondestructive assay (NDA) techniques for the measurement of uranium and plutonium in 55-gal barrels of solid waste is reported. The NDA techniques reviewed include passive gamma-ray and x-ray counting with scintillator, solid state, and proportional gas photon detectors, passive neutron counting, and active neutron interrogation with neutron and gamma-ray counting. The active neutron interrogation methods are limited to those employing isotopic neutron sources. Three generic neutron sources (alpha-n, photoneutron, and exp 252 Cf) are considered. The neutron detectors reviewed for both prompt and delayed fission neutron detection with the above sources include thermal ( exp 3 He, exp 10 BF sub 3 ) and recoil ( exp 4 He, CH sub 4 ) proportional gas detectors and liquid and plastic scintillator detectors. The instrument found to be best suited for low-level measurements (< 10 nCi/g) is the exp 252 Cf Shuffler. The measurement technique consists of passive neutron counting followed by cyclic activation using a exp 252 Cf source and delayed neutron counting with the source withdrawn. It is recommended that a waste assay station composed of a exp 252 Cf Shuffler, a gamma-ray scanner, and a screening station be tested and evaluated at a nuclear waste site. 34 figures, 15 tables. (ERA citation 05:025365)